1. Field of the Invention
Embodiments of the present invention relate generally to a semiconductor wafer chemical mechanical planarization system having a substrate transfer shuttle for transferring a workpiece and methods related thereto.
2. Background of the Related Art
In semiconductor wafer processing, the use of chemical mechanical planarization, or CMP, has gained favor due to the enhanced ability to increase device density on a semiconductor workpiece, or wafer. As the demand for planarization of wafers as part of a semiconductor fabrication process increases, the requirement for higher system (i.e., tool) performance with enhanced wafer planarization has also increased.
Two such CMP systems that address these issues are described in U.S. Pat. No. 5,804,507, issued Sep. 8, 1998 to Perlov et al. and in U.S. Pat. No. 5,738,574, issued Apr. 15, 1998 to Tolles et al.. The Perlov et al. and Tolles et al. patents are incorporated herein by reference in their entirety. The Perlov et al. and Tolles et al. patents disclose a CMP system having a planarization apparatus that is supplied wafers from cassettes located in an adjacent liquid filled bath. A transfer mechanism, or robot, facilitates the transfer of the wafers from the bath to a transfer station. From the transfer station, the wafers are loaded to a polishing head. A carousel delivers the polishing head and wafer to various planarization stations where the wafers are planarized by moving the wafer relative to a rotating polishing material disposed on the planarization station in the presence of a polishing fluid. After completion of the planarization process, the wafer is returned back through the pedestal to the proper cassette located in the bath.
Another CMP system is disclosed in U.S. Pat. No. 5,908,530, issued Jun. 1, 1999 to Hoshizaki et al. and is incorporated herein by reference in its entirety. Hoshizaki et al. teaches an apparatus for planarizing wafers wherein the wafer held against a polishing material that is moved in an x/y motion. The relative motion between the polishing material and wafer results in the wafer surface being subjected to uniform velocity across the wafer""s diameter. The uniform velocity across the wafer""s surface advantageously provides a uniform material removal rate. Although Hoshizaki et al. provides excellent wafer surface processing and extended tool life, increased wafer throughput and expanded process versatility are desired as more device fabrication procedures include planarization steps.
Therefore, there is a need for an apparatus that facilitates increased throughput in a chemical mechanical wafer planarization system.
One aspect of the invention provides a system for processing a workpiece. In one embodiment, the system includes a processing module and a substrate transfer shuttle. The processing module includes a polishing surface and at least one polishing head disposed above the polishing surface. The substrate transfer shuttle is movable between at least a first position and a second position where the second position is disposed adjacent the polishing head. At least one nest is disposed in the substrate transfer shuttle. The nest transfers the workpiece to the processing head.
In another aspect of the invention, an apparatus for transferring a workpiece is provided. In one embodiment, the apparatus includes a base plate and an insert pad having a fluid distribution plate disposed therebetween. The base plate includes at least a first port and a second port for coupling to a fluid supply. The insert pad includes a plurality of centering fingers and a plurality of lift fingers. The centering fingers are fluidly coupled to the first port through the insert pad and distribution plate. The lift fingers are fluidly coupled to the second port through the insert pad.
In other aspect of the invention, a method for transferring a workpiece is provided. In one embodiment, the method includes the steps of placing the workpiece in a nest, centering the workpiece in the nest, and providing a fluid between the workpiece and nest during the centering step. In another embodiment, the method includes the steps of placing the workpiece in a nest disposed in a first position, moving the nest laterally to a second position adjacent a polishing head coupled to a first processing module, and transferring the workpiece from the nest to the polishing head.